Core type winder drive



March 25, 1952 G. CAWLEY ET CORE TYPE WINDER DRIVE Filed June 3, 1949 MOTOR SPEED w =consz INVENTORS GfO/PGE' CAM EV HOW/7R0 M GROW/V ATTORN EYS Patented Mar. 25, 1952 CORE TYPE WINDER DRIVE George Cawley, Upper Montclair, and Howard M. Brown, Wood-Ridge, N. J.

Application June 3, 1949, Serial No. 97,014

11 Claims. 1

This invention relates to winding machines for winding material in strip or sh et form into rolls as in the manufacture of electrical condensers ior example, and more particularly to a method and means for maintaining a constant tension in the material so wound.

In the art of winding cores of paper or foil or similar materials, it is often desirable that the material be wound at the same tension in all layers. As the diameter of the roll of material being wound increases, the torque applied to the mandrel on which the material is being wound must be increased in proportion to the diameter of the roll if the tension in the material is to be kept constant. Various expedients have been heretofore proposed for this purpose employing slipping clutches or belts between the source of power and the winding mandrel. The present invention furnishes instead an electrodynamic means to this end.

According to the present invention the winding mandrel is driven by a constant speed motor, for example an induction motor. Both the field and the armature members of the motor are rotatably mounted and one member is coupled to the winding mandrel while the other member is coupled to a generator. The motor drives both generator and winding mandrel, driving the mandrel in one direction and the generator in the opposite direction. The speed of the mandrel is determined by the rate at which the material to be wound is supplied and by the diameter of the roll. Apparatus is available which delivers the material to be wound at constant linear speed regardless of the tension exerted on the material by the mandrel, and such apparatus is advantageous for the supply to the mandrel of the material to be wound. With the material supplied at a constant linear speed the angular speed of the mandrel is inversely proportional to the diameter of the roll thereon. The difference between the mandrel speed and the constant speed of the motor appears between the generator armature and field, the motor drawing whatever power is necessary to drive the generator at this speed.

As the material winds up on the mandrel, increasing the diameter of the roll of material thereon, the mandrel slows down and enforces a corresponding speed increase on the generator. The increase in generator speed requires an increased torque which is made available by the motor and which appears also at the mandrel, keeping the tension in the material wound constant to a first approximation.

Since the generator speed is a nonlinear function of the roll diameter, the generator torque does not with constant applied field and connects ed load increase quite proportionally with the roll diameter, and our invention provides means whereby the generator torque may be caused to increase more than proportionally with generator speed, if a high degree of constancy in the tension of the material wound is desired.

In the accompanying drawings- 7 Fig. l is a diagrammatic view of an embodiment of our invention;

Fig. 2 is a generalized plot of the relation between roll radius and generator speed in the device of Fig. 1;

Fig. 3 illustrates a modification of the embodiment of Fig. 1; and

Fig. 4 illustrates a further modification of the embodiment of Fig. 1.

In Fig. 1 a strip of material 5 to be wound up into a roll is supplied from a supply roll I over a constant speed delivery device 9 to a winding mandrel H.

A drive motor generally indicated at [5 includes a field producing element [6 and an armature element [8, both of which are mounted for rota-1 tion with respect to each other and with respect to a base It. Thus in the embodiment shown the field element [6 is mounted in bearings 20 aflixed to the base and the armature element is mounted in bearings 2| forming part of the field element. Power is supplied to the field element 16 by conductors 23 making contact at slip rings 24. The armature element I8 is linked through a suitable shaft 25 or other mechanical coupling to the armature 28 of a generator generally indicated at 36. The field element I6 is similarly coupled to the mandrel H. The generator has a fixed field winding 3| connected to terminals 32. Brushes 3% connect the generator armature voltage to a set of terminals 36 which may be connected by means of a suitable switch 31 to a load such as the resistance 48. The field winding 3! is supplied with direct current; exciting voltage at its terminals 32 from a suitable source 42, regulation being available at a rheostat 43. A brake 45 is arranged to releasably lock the mandrel.

At the beginning of the winding operation, the strip material 5 is threaded onto the stationary mandrel, for example at a slit 12 provided for that purpose. With the motor 15 turning at rated speed the generator 30 is driven at the same speed. The torque required to drive the generator at this speed is determined by the product of its field flux and armature current. The field flux is determined by the voltage available from the source 42 and the setting of the rheostat 43. With a fixed load such as the resistance 40, the armature current is proportional to the voltage appearing at the armature terminals 36 and this in turn is proportional to the product of the field flux and the generator speed. With fixed field excitation and fixed load the generator torque is' therefore proportional to generator speed. It may be established for the condition at which the generator turns at the motor speed at any desired level by appropriate choice of the load resistance 40 and by adjustment of the field rheostat 43.

The winding operation is commenced by un locking of the brake 45, the material delivering device 9 being simultaneously set into operation by conventional mechanism linked to the brake release lever, not shown.

Under the torque appearing between the field I6 and the armature iii of the motor, and which is determined by the generator adjustment, the mandrel ll begins to rbtate at once, coming within a negligible time to the angular speed determined by the radius of the mandrel itself and the linear speed at which the strip is delivered. The generator 39 thereupon assumes a speed equal to the difference between the speed of the motor and the mandrel, and the torque applied to the mandrel is determined by the torque required to drive the generator at this speed, with a given condition of field excitation and a given load resistor is. The generator is adjusted so that the torque required to drive it at this initial speed equals the product of the desired tension in the strip and the radius of the mandrel itself.

As the strip material accumulates into a roll on'the mandrel, the angular speed of the mandrel falls; and the speed of the generator increases correspondingly. As the speed of the generator increases, the torque required to drive it increases proportionally so that the torque at the mandrel increases also, compensating for the increase in radius of the roll 5 on the mandrel.

The, relation between generator speed and roll radius may be expressed as follows:

wherein wg is the angular speed of the generator, mm is the angular speed of the motor, V is the linear speed at which the strip 5 is delivered by the delivery device 9, and r is the radius of the roll of material on the mandrel.

A generalized plot of the relation expressed in this equation is shown in Fig. 2, from which it is apparent that r and (03 are nonlinearly related. Fig. 2 of course assumes a fixed speed of delivery of the strip material 5. Thus although the generator speed rises as the radius of the roll 6 on the mandrel increases, the slope of the curve decreases with increasing roll radius, and in fact approaches asymptotically to the motor speed as a limit as the roll radius grows very'large.

By proper choice of motor speed in relation to the range of roll diameters to be worked, the range of generator speeds may be kept on the substantially linear portion-of the curve at the left of the figure, where the roll radii are small.

If very large cores are to be wound however, especially cores wherein the difierence between the inner and outer radii is great, the curvature co =w of the generator speed-roll radius characterist c becomes so large over the range in roll diameters involved as to require supplementary correction measures if the tension in the material wound onto the rolls is to be kept even approximately constant. In order to correct for the curvature of the characteristic, it is necessary to cause the torque demanded by the generator to increase more than linearly with the generator speed. This change in the torque characteristic of the generator may be achieved either by increasing the field excitation of the generator, or by increasing the current drawn from the armature, or by both. If the field excitation is increased, .the torque required will increase both because the flux is a factor in the torque required and because an increased flux will raise the armature voltage and hence the current drawn from the generator by a fixed load.

Fig. 3 illustrates diagrammatically a mechanism for increasing the field excitation supplied to the generator as the diameter of the roll of material on the mandrel increases. The mandrel is shown at H as before with a roll 5 of the strip material 5 in the course of accumulation thereon. A follower roller rides on the roll 8 and is mounted on a lev er 52 pivoted at 554 in the frame which supports the mandrel. A lever arm 58 afiixed to the lever 52 carries a contact 58 on its end which makes contact with a rheostat 60. The circuit which supplies the field winding 3% of the generator includes the rheostat 6i] and contact 58, so that the fraction of the rheostat 60 inserted in series with the field winding depends on the position of the contact 58 and hence on the radius of the roll of material on the mandrel. When the winding begins, all of the rheostat 6i! is included in series withthe generator field winding and the generator field flux is at a minimum. As the radius of the roll im creases, the contact 58 removes more and more of the rheostat 68 from the field circuit, increasing the flux produced in the field winding of the generator. By properly proport'ioning the rheostat 39, the flux in the generator may caused to increase with the increasing radius of a roll of material on the mandrel at the rate required to make the generator torque a linear function of the roll radius.

In Fig. 4 is illustrated an alternative modified tion in which the field excitation remains viii changed but in which the load on the generator armature is increased by reduction of the load resistance. The generator armature 28 feeds into a load comprising a variable resistance 65. A movable contact ii? on the resistance 65 connects with one of the armature terminals 36 and is supported on a lever ee pivoted at The lever 63 is linked to the armature of a solenoid iii whose coil is connected across the generator armature terminals 36. The movable contact 67 is loaded, by a spring or as illustrated in the figure by means of a cam i2 and a Weight it, so as to in clude the whole of the resistance 65 in series with. the generator armature when the solenoid is deenergized or below a critical value. As the generator speed increases with increasin radiusof the roll of material on the mandrel, the armature output voltage rises so that the current through the coil of the solenoid iii increases, drawing the movable contact ti in the direction which reduces the effective value of the load resistance 65. By a proper shaping of the cam '12 the linearly increasing generator voltage applied to the solenoid coil may be caused to effect a suitv able reduction in the effective value of the resistance {65 so that the torque required of the generator will again be linear with the generator speed.

The generator employed may be either a direct current or an alternating current machine, a die rect current machine being perhaps most convenient. If an alternating current machine is used, care should preferably be taken to keep the connected load substantially nonreactive, and if the modification of Fig. 4 is employed, the solenoid '10 should be equipped with a shading coil or other means to prevent the force exerted on the solenoid armature from falling to zero upon reversal of the direction of current flow.

We claim:

1. In a. winding machine, a base, a mandrel mounted for rotation relative to the base for reception of the material to be wound, a substantially constant speed motor having afield member and an armature member, said motor members being mounted for rotation with respect to each other and with respect to the base, a generator having a field member and an armature member, one of the generator members being fixed relative to the base and the other generator member being mounted for rotation relative to the base, a linkage coupling one of the motor members with the mandrel, a linkage coupling the other motor member with the rotatable generator member, and a passive load electrically connected to the winding of the generator armature member.

2. In a winding machine in which the material supplied to the mandrel as the instantaneous diameter of the roll of material on the mandrel increases, said means comprising a substantially constant speed motor having a field member and an armature member, said field and armature members being mounted for rotation with respect to each other and with respect to the base of the Winding machine, a generator, a coupling between the mandrel and one of the motor members, a coupling between the generator armature and the other of the motor members, and a passive load electrically connected to the generator armature winding.

3. In a winding machine in which the material to be wound is fed to a winding mandrel at constant linear speed, means to increase the torque supplied to the mandrel in proportion to the instantaneous diameter of the roll of material on the mandrel, said means comprising a substantially constant speed motor having a field member and an armature member, said field and armature members being mounted for rotation with respect to each other and with respect to the base of the winding machine, a generator, a coupling between the mandrel and one of the said members, a coupling between the generator armature and the other of the said members. and means to compensate for the nonlinear relation between generator speed and the diameter of the roll of material wound up on the mandrel, said last-named means comprising means for reducing the resistance in series with the winding of the generator armature with increasing generator armature speed.

4. In a winding machine in which the material to be wound is fed to a winding mandrel at constant linear speed, means to increase the torque supplied to the mandrel in proportion to the instantaneous diameter of the roll of material on the mandrel, said means comprising a substantially constant speed motor having a field member and an armature member, said field and armature members being mounted for rotation with respect to each other and with respect to the base of the winding machine, a generator, a coupling between the mandrel and one of the said members, a coupling between the generator armature and the other of the said members, and means to compensate for the nonlinear relation between generator speed and the diameter of the roll of material wound up on the mandrel, said last-named means comprising means for increasing the electrical load imposed upon the generator armature winding with increasing diameter of the roll of material wound up on the mandrel.

5. In a winding machine in which the material to be wound is fed to a winding mandrel at constant linear speed, means to increase the torque supplied to the mandrel in proportion to the instantaneous diameter of the roll of material on the mandrel, said means comprising a substantially constant speed motor having a field member and an armature member, said field and armature members being mounted for rotation with respect to each other and with respect to the base of the winding machine, a generator, a coupling between the mandrel and one of the said members, a coupling between the generator armature and the other of the said members, and means to compensate for the nonlinear relation between generator speed and the diameter of the roll of material wound up on the mandrel, said last-named means comprising means for increasing the voltage applied to the generator field winding with increasing diameter of the roll of material wound up on the mandrel.

6. In a Winding machine including a base, a mandrel mounted for rotation relative to the base for reception of the material to be wound, means to deliver the material to be wound to the mandrel at constant linear speed, a substantially constant speed motor having a field member and an armature member, said motor members being mounted for rotation with respect to each other and with respect to the base, the generator having a field member and an armature member, one of the generator members being fixed relative to the base and the other generator member being mounted for rotation relative to the base, a linkage coupling one of the motor members with the mandrel, a linkage coupling the other motor member with the rotatable generator member, and a load electrically connected to the generator armature member, means for increasing the field excitation of the generator with increasing diameter of the roll of material wound up on the mandrel, said means comprising a variable resistance connected in series with the winding of the generator field me -iber, movable contact arranged on the vari ole re-- sistance for varying the resistance value a follower adapted to ride on the roll at m in wound up on the mandrel, and a linkage so coupling the follower with the movable contact that the value of the variable resistance is reduced as the radius of the roll of material on the mandrel increases.

7. In a winding machine including a base, a mandrel mounted for rotation relative to the base for reception of the material to be wound, means to deliver the material to be wound to the mandrel at constant linear speed, a substantially constant speed motor having a field member and an armature member, said motor members being mounted for rotation with respect to each other and with respect to the base, the generator having a field member and an armature member, one of the generator members being fixed relative to the base and the other gen l spect to each other and with respect to the base,

on the mandrel, said means comprising a variable resistance connected in series with the Winding of the generator field member, a movable contact arranged on the variable resistance for varying the resistance value thereof, a follower adapted to ride on the roll of material wound up on the mandrel, and a linkage so coupling the follower with the movable contact that the value of the variable resistance is reduced as the radius of the roll of material on the mandrel increases. i

8. In a winding machine including a base, a

mandrel mounted for rotation relative to the base for reception of the material to be Wound,

a substantially constant speed motor having a field member and an armature member, said motor members being mounted for rotation with respect to each other and with respect to the base, the generator having a field member and an armature member, one of the generator members being fixed relative to the base and the other generator member being mounted for rotation relative to the base, a linkage coupling one of v the motor members with the mandrel, a linkage coupling the other motor member with the rotatable generator member, and a load electrically connected to the generator armature member, means for increasing the torque required to drive the generator more than proportionally with increasing generator speed, said means comprising a variable resistance electrically connected in series with the winding of the generator armature member, a movable contact arranged on the variable resistance adapted to vary the resistance value thereof, a pivoted lever carrying the movable contact, a cam affixed to the lever, a weight dependent from the cam, the pull of the weight on the cam tending to rotate the lever about the pivot in a first direction such as to maximize the value of the variable resistance, and a solenoid having its coil connected across the terminals of the winding of the generator armature member, the armature of the solenoid being coupled to the lever so as to rotatethe lever in the opposite direction upon energization of the solenoid.

9. In a winding machine including a base, a

the generator having afield member and an armature member, one of the generator members being fixed relative to the base and the other generator member being mounted for rotation relative to the base, a linkage coupling one of the motor members with the mandrel, a linkage coupling the other motor member with the rotatable generator member, and a load electrically connected to the generator armature member, means to increase the load connected to the generator as the generator speed increases with increasing diameter of the roll of material wound up on the mandrel, said means comprising a variable resistance electrically connected in series with the winding of the generator armature member, a movable contact arranged on the variable resistance and varying the resistance value thereof, a; pivoted lever carrying the movable contact,

a cam aflixed to the lever, a weight dependent from the cam, the pull of the weight on the cam tending to rotate the lever about the pivot in a first direction such as to maximize the value of the variable resistance, a solenoid having its coil connected across the terminals of the winding of the generator armature member, the armature of the solenoid being coupled to the lever so as to rotate the lever in the opposite direction upon energization of the solenoid.

10. In a machine for winding sheet material at constant tension, means for supplying the material to be wound at constant linear speed, a winding mandrel, a substantially constant speed motor having a field member and an armature member both rotatably mounted with respect to the material supply means, a coupling between the mandrel and one of the motor members, a generator coupled to the other of the motor members, and a passive load electrically connected to ,the terminals of the generator armature.

11. In a machine for winding sheet material at constant tension, means for supplying the material to be wound at constant linear speed, a winding mandrel, a substantially constant speed motor having field and armature members both rotatably mounted with respect to the material supply means, a coupling between the mandrel and one of the motor members, a direct-current generator coupled to the other of the motor members, and a passive load electrically connected to the terminals of the generator armature.

- GEORGE CAWLEY.

HOWARD M. BROWN.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS .Number Name Date 805,188 Dey Nov. 21, 1905 1,828,943 Rossman Oct. 27, 1931 

